Correct read past end of list error in format enumeration

When format lists are split across mutliple caps structures,
each list should be read up to its size, not the aggregate of
all formats.

lib/libv4l-gst/gst-backend.c

@@ -517,15 +517,17 @@ get_supported_video_format_cap(GstElement *appsink, struct fmts **cap_fmts,
 	fmts_num = 0;
 
 	for (j = 0; j < structs; j++) {
+	        gint num_cap_formats;
 		structure = gst_caps_get_structure(caps, j);
 		val = gst_structure_get_value(structure, "format");
 		if (!val)
 			continue;
 
-		list_size += gst_value_list_get_size(val);
+		num_cap_formats = gst_value_list_get_size(val);
+		list_size += num_cap_formats;
 		color_fmts = g_renew(struct fmts, color_fmts, list_size);
 
-		for (i = 0; i < list_size; i++) {
+		for (i = 0; i < num_cap_formats; i++) {
 			list_val = gst_value_list_get_value(val, i);
 			fmt_str = g_value_get_string(list_val);